Vacuum tube



Dec. 18, 1934.

P. SPENCER 1,934,81

VACUUM TUBE OriginalFiled June 3, 1929 I 11 ml INVENTOR Patented Dec. ,18, 1934 VACUUM TUBE Percy L. Spencer, Medford, Mass assignor to Raytheon Production Corporation, Cambridge,

Mass., a corporation of Delaware Application June 3, 1929, Serial No. 367,947 Renewed February I, 1934 3 Claims.

5 they are commonly termed-for the clean up of gas in vacuum tubes are generally disposed in capsules which are welded to a wire which itself is welded to some portion of the tube structure. It has been customary to dispose the getter capsule away from electrodes proper in order to prevent theundesirable flashing of the getter when the electrodes themselves are heated to remove occluded gases. As is well known nickel is the material out of which the plate or anode electrode of vacuum tubes are usually made. If misch metal is used as a getter and disposed adjacent a nickel surface, a low melting alloy is formed which tends to flash the getter at an undesirable time during the manufacture thereof. By my invention I am enabled to dispose the getter capsule in a convenient manner directly on the wall of one of the electrodes even if made of nickel. The composition of the getter material is such that during the ordinary heating of the electrode to remove occluded gases no low' melting alloy with the getter will be formed and hence the getter will not be flashed. In order to actually flash the getter, the electrode proper may be heated by induction or in any other manner to a sufliciently high temperature to flash the material.

The single flgure shows the tube assembly. Stem 1 terminates in a press 2 in which are sealed various supporting wires. These supporting wires support among other electrodes an anode or plate electrode 5. Upon one surface of this electrode is welded a hat shaped metal capsule 6'within which the getter material is disposed. Capsule 6 it will be noted has a flat flange 7 bearing on the surface of the plate 5. This capsule may be welded in one or two spots on the plate. Due to the unevenness of the metal flange 7, small openings are formed between the flange and the plate which allow the getter vapor to escape.

The getter material which I use is an alloy or NI TED STATES PATENT OFFIC compound substantially of cerium and iron or ferrocerium. This material is well known and is customarily used as the spark producing element in mechanical lighters.

The entire assembly is disposed in an envelope of glass in the customary manner.

An exhaust pump removes as much air as possible. During this pumping the electrodes are strongly heated by bombardment or high frequency in the usual manner to remove occluded gases.

course of manufacture such electrodes are not heated to a sufficiently high temperature to flash the ferrocerium getter. After the occluded gases have been removed, the tube is sealed in the usual manner and the getter may then be flashed. This is done by heating the electrode carrying the getter to a very high temperature.

I claim:

1. In an electron discharge device, an evacuated envelope, a nickel electrode of extended area within said envelope, and a getter consisting solely of ferrocerium directly secured to said electrode.

2. The method of processing a vacuum tube having electrodes of the type consisting largely taining said temperature during said heating pe- In the usual 10 of nickel, which comprises mounting directly on 2 riod below the value at which the getter would flash, sealing up said vacuum tube and subsequently heating said capsule to a temperature at which the ferrocerium flashes and cleans up residual gases within the tube.

3. In an electron discharge device, an envelope, an electrode containing a considerable proportion of nickel, said electrode having an extended area within said envelope, and a getter consisting solely of ferrocerium directly secured to said electrode. 

